a underwear 还是 AN UNDERWEAR?

How would you like to wear the same underwear (内衣裤) for weeks? Owing to the work that has gone into developing intelligent materials, this may not be as 41 as it sounds. Self-cleaning clothes have now been created, and these new materials provide 42 resistance to dirt as well as water. As a result, they require much less cleaning than traditional materials.
The creation of self-cleaning clothes provides an example of how nature helps scientists develop better products. This self-cleaning nature is known as the “lotus effect”. The name comes, of course, from the lotus leaves, which are famous for growing in muddy lakes and rivers while remaining almost 43
clean. By observing nature, scientists are 44 the qualities of the lotus leaves to the materials they have engineered. Because of this, some remarkable new products have been 45 . Among them are special windows that are resistant to dirt and water. A special 46 on these windows not only prevents dirt from sticking to their surfaces, but also allows dust to be easily washed off by the rain. In fact, these new windows have already been 47 to some cars. Even when traveling at high speed through rain, these cars never have to use their windshield wipers (雨刮器).
Although we have already seen some practical applications, even more dramatic 48 will be made in the future, and they will, perhaps, change our world completely. Undoubtedly, technology is an important development, and it will have an even bigger 49 on our lives.